Field of the Invention
The present invention relates to a transdermal patch comprising water soluble microneedles and to a method of manufacturing the same.
Background Information
Conventionally, one means of administering a drug or drugs noninvasively via the body surface of an organism, such as the skin or a mucous membrane, is to perform transdermal administration via a transdermal patch. Furthermore, to efficiently adsorb a drug or the like from a transdermal patch onto the body, a preparation called a microneedle sheet or a microneedle patch is being developed whereon the drug is adsorbed by minute needles having a high aspect ratio, which are referred to as so-called microneedles, and those minute needles are disposed in an array on a sheet.
Among such microneedles, there is one that is configured using a water soluble raw material such that it is dissolved by moisture existing within the skin, moisture given off by the skin, and the like. In addition, it is also possible to use moisture that exists in places other than the skin; for example, Patent Literature 1 (Japanese Unexamined Patent Application Publication No. 2011-194189) describes an example wherein a cosmetic liquid containing sheet is brought into contact with a transdermal patch from the side of the transdermal patch opposite that of the skin, and the moisture contained in the cosmetic liquid containing sheet is introduced to the microneedles.
A microneedle array in Patent Literature 1 is formed using an in vivo soluble substance, such as hyaluronic acid or a collagen, as a raw material. Here, an example is described wherein the microneedle array is formed using as a raw material a substance that dissolves in water in particular. Furthermore, to assemble the microneedle patch, an adhesive tape, which is made of polyethylene and from which the center portion has been cut out, is attached to the circumference of an elliptical substrate of the microneedle array of Patent Literature 1. This elliptical microneedle array has a long side that is approximately 30 mm and a short side that is approximately 20 mm.
In addition, Patent Literature 2 (Japanese Unexamined Patent Application Publication No. 2010-94414) describes a manufacturing method wherein a microneedle sheet is formed of a water soluble macromolecular substance, and a microneedle sheet solidified body is bonded to a support body sheet via an adhesive layer.